Method of making insulating tubes



Sept. 6, 1938.v A. ARUTUNOFF 'METHOD OF MAKING INSULATING TUBES FiledNov. 4, 1957 mvEzvroR 9mm/off ATTORNEY Patented Sept. 6, 1938 UNITEDvSTATES PATENT QFFICE poration of Delaware My invention relates toamethod of making insulating tubes for slot insulation of electricalmotors.

5 my copending allowed application, Serial No.

73,693, led April 10, 1936, for a Method of making insulating tubes. A

' Certain types of electrical motors sueltas submergible electric motorsfor use in oil wells are of very great length and of small diameter. Forexample, a 75 horse power motor, designed with a rotor making 3600revolutions per minute has a inch outer diameter and a length of activeiron or stator of 16 feet. Similarly, a 100 horse power motor of thesame outer diameter has a length of active iron of 2l feet. Slotinsulation otsuch long stator must take the form of a long tube having awall thickness of from .02 to .025 of an inch, and a cross section'ofapproximately 0 .25 square inch. Tubes of such length and dimensions arenot obtainable in open market. i

One object of my invention is to providel a method of making longinsulating tubes. Another object of my invention is to provide 5 amethod of making long insulating tubes of predetermined cross sectionalshape.

Other and further objects of my invention will appear from the followingdescription.

' Insulating tubes for the slots of the stator of l an electric motor ofthe length involved in the instant case are not round but are formed toilt the shape of the slots of the stator.

In the accompanying drawing which forms part of the instantspecification and is to be read in conjunction therewith and in whichlike reference numerals are used to indicate like parts in the variousviews;

Figure 1 is a perspective view of anolling bench adapted to be used incarrying out the process of my invention. 'l i Figure 2 is a sectionalend view of the bench of Figure 1 showing the position of partswhen therolling is about to take place.

Figure 3 is a view similar to that shown in Figure 2, showing therolling operation commenced.

Figure 4 is a perspective view of, a section showing a heating devicefor baking the tubes in the L desired form. y

Figure 5 is an enlarged view showing one method of assembling thematerial from which the insulating tubes may be made. Y

Figure 6 is a view showing the insulating tube being pulled off theform.

Figure 'I is a modification showing the moldvThis application is acontinuation in part of Reda Pump Company, Bartlesville, Okla., a cor-Appucaaon November 4, 1931, serial No. 172,762

s claim. (cl. sas- 91) ing operation conducted at ordinary temperatures.

The bench consists of a working surface I which may be made of wood,brass or anyother suitable material, provided with a longitudinally 5extending groove 2 in which a rod l is adapted to be placed. The rollingrod l is provided at one end with a crank 2i by which it is adapted tobe rotated. The rolling rod 3 is formed with a longitudinally extendingslot 4. Secured to the l0 working bench i are a plurality of brackets Ito which are pivoted members 6 carrying angle members 8. Weights 1areadapted to be positioned upon angle members I by means of anysuitable connection, as for example slots I. The 15 angle members lsupport side pieces to which rollers lli are pivoted. The arrangement issuch that rollers L0 bear against rolling rod 3 to insure a tightlyrolled tube. The working surface I may be of any suitable length and islong enough to 20 take the longest insulating tube it is desired tofabricate. There are a number of pivoted mem bers 6 so that these may beemployed in the region in which the rolling of the insulating tubes istaking place.

In the manufacture of insulating tubes according to the method of myinvention, a full length strip of insulating paper is placed upon theworking bench and one edge thereof is engaged in the slot 4 of therolling rod 3. The rod is then given 30 at least one complete turn tostart the rolling ,of the paper along its length. The insulating paperis then given a coat of shellac. lacquer, or other suitable material,and additional insulation such as a thin mica sheet or the like may beplaced over the shellac. Additional lacquer, shellac, or the like isplaced over lthe mica or other suitable insulating material and then therod is loaded by moving pivoted members l to the tion shown in Figures 2and 3. Thev40 weights 'Il which are supported by the members f6 exert apressure upon rollers il. The crank of the rod is then revolved, forminga tube which is round. The round tube is then removed. It is notnecessary to permit the lacquer or shel'lac 45 or the like to fullydrysince there is a complete turn of insulating paper adjacent the rodwhich is not covered with adhesive. If desired, the tube may bepermitted to dry for a short time.

When the rolling rod l is removed,` a forming rod i9 is inserted throughthe cylindrical tube. This rod I9 is of the shape of the slot in'whichthe insulating tube is to be used. 'I'he tube on the forming rod is thentransferred into a baking device which is shown in Figure 4, accordingto one `are to be used. A number of suitable forms of slots may be madein the baking device. The bottom of the metal block is provided with arecess in which is housed a heating element il. These heating elementsare well known to the art and form no part o! my invention. The heatgenerated by the heating element is transmitted through the metal block.'I'he forming rod with the tube thereon has been placed in a slot l5 and`the cover plate I8 which is of sumcient weight to iirmly close the slotis placed thereover. The tube is baked for a suitable interval of timetoaccomplish perfect adhesion of the various layers of lacquer orshellac. A temperature of from 200 to 350 F. will suffice for thebaking. After baking, the forming rod is withdrawn from the end of thetube sufilciently to tie an end with wire as shown in Figure 6. The tubewith the rod thereon is pushed into the slot of the stator. Afterinsertion in the slot, the tube is held by the wire-wrapped end, whilethe forming rod is withdrawn. The surplus ends of the insulating tubeare then cut of! and the stator is ready for threading with wire.

Referring now to Figure 4, if time is not oi' the essence, the moldingmay take place under atmospheric temperature. In this case the tube isdrawn while in a soft state, from the cylindrical forming mandrel intothe mold and, while in the mold, is permitted to take the desired form.No core is used in this mode of proceeding, as it is desirable to havethe interior of the tube open to the air to permit free circulationwhich will aid in the drying of the tube.

It will be observed that I have accomplished the objects of myinvention. I have provided a method of producing insulatingr tubes oigreat length for slot insulation. I have provided a method of formingtubes oi the desired cross sec- Having thus described my invention, whatIV claim is:

1; A method for making insulating tubes including the steps of partiallyrolling a sheet oi flexible material about a cylindrical form. applyinginsulating adhesive to an unrolled portion oi said sheet, continuing therolling of said sheet to form a tube, removing the cylindrical form fromsaid tube while said adhesive is in a soft state, inserting a formhaving a predetermined cross sectional shape into said tube, and moldingsaid tube about said form at elevated temperature.

2. A method of making insulating tubes including the steps of partiallyrolling a sheet of iiexible insulating material about a cylindricalform, applying adhesive to the unrolled portion of Isaid sheet,continuing the rolling of said sheet to form a tube, removing thecylindrical form from said tube while said adhesive is in a soft state,inserting a form having a predetermined cross sectional shape into saidtube, and molding said tube about said form at elevated temperatures.

3. A method of making insulating tubes for electric motors whichinsulating tubes are of great length with respect to their crosssectional area, including the steps of partially rolling a sheet ofiiexible insulating material about a cylindrical form, applying adhesiveto the unrolled portion of said sheet, continuing the rolling of saidsheet to form a tube, removing the cylindrical i'orm from said tubewhile said adhesive is in 'a soit state, inserting said tube in a formhaving a predetermined cross sectional shape and molding said tube tosaid shape.

Annuals ARUTNOFF.

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